Infant Brain Injury – The Contrecoup-Coup

The Contrecoup–Coup Phenomenon

A New Understanding of the Mechanism of Closed Head Injury

Laura B. Drew,1,* and William E. Drew,2

1Oakwood High School, Dayton, OH and 2Wright-Patterson Medical Center,
Wright-Patterson AFB, OH

Abstract

Acommon observation in closed head injuries is the contrecoup brain injury. As the
in vivo brain is less dense than the cerebrospinal fluid (CSF), one hypothesis explaining
this observation is that upon skull impact, the denser CSF moves toward the site of
skull impact displacing the brain in the opposite direction, such that the initial impact
of the brain parenchyma is at the contrecoup location.
A simple model was developed consisting of a balloon filled with water of density
1.00 g/mL enclosed in a clear plastic jar containing salt water of density 1.04 g/mL, simulating
the same relative densities of the CSF and brain. The initial movement of the balloon,
modeling the brain, was toward the contrecoup location with subsequent movement
toward the coup location.
The pattern of brain injury in which the contrecoup injury is greater than the coup
injury is a result of initial movement of the brain in the contrecoup location.
During the process of closed head injury, the brain parenchyma is initially displaced
away from the site of skull impact and toward the contrecoup site resulting in the more
severe brain contusion.

Introduction

When an individual suffers a closed head injury, forces on the brain within the cranial vault result in injury to the brain parenchyma. The exact mechanisms by which these forces injure the brain have been a matter of considerable debate. Giovanni Battista Morgagni, considered the father of anatomic pathology, and Henri Francois LeDran postulated
theories on the mechanisms of closed head injury in the 18th century (1). In 1766, a debate held in Paris and sponsored by the Academy of Surgeons, aggressively defended competing theories for the mechanism of coup and contrecoup injuries. For more than 200 years, the debate has continued. The primary matter of scientific curiosity is the frequent observation that the injury to the brain opposite the location at which the skull strikes an external object is frequently more severe than the injury to the brain that occurs adjacent to the area of skull contact. The following definitions are provided for clarity: the coup injury to the brain is the contusion to the brain that occurs at the area of brain adjacent to the location at which the skull impacts with a fixed external object. In contrast, the contrecoup injury to the brain is the contusion to the brain that occurs at the area of brain opposite the area

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Journal Neurocritical Care

Publisher Humana Press Inc.